(1) Field of the Invention
The invention relates to a beam combiner for combining two illuminating beams of a light scanning microscope that can be independently scanned.
(2) Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
In light scanning microscopy, there is a need to overlay two or more scanned illuminating beams. The overlay of a fluorescence excitation beam with a manipulation beam that manipulates the fluorescence properties of the sample at specific places (e.g., by bleaching the sample) is referenced as an example.
Dichroic beam splitters are known in the art use as for beam combiners. They have the limitation that it must be possible to adequately distinguish between the wavelengths of the light beams to be combined. Also, there is only limited flexibility with respect to the wavelengths used for a given beam splitter. The result is that, when the wavelength of one or both illumination beams is changed, the dichroic beam splitter must be exchanged. Changing mechanisms for this purpose are known, but they must meet high precision requirements and therefore are costly to manufacture.
So-called neutral splitters are one alternative. While they are in no way restrictive with regard to the wavelengths that are used, they necessarily result in losses of intensity when the illuminating beams are combined.